Dishwasher status indicators help dishwashing machine users determine whether dishes in a dishwasher are dirty or clean. It is important to have a simple and reliable indicator because users often do not unload the entire batch of dishes after a cleaning cycle has been run; instead they often leave clean dishes in the dishwasher and unload them one at a time as they are needed. This causes confusion in the household, with household members unsure of whether the dishes in the dishwasher are clean or dirty.
Various types of dishwasher status indicators are known, such as those disclosed in U.S. Pat. Nos. 5,839,458, 6,196,239, and 5,477,872. The devices disclosed in these patents rely on moving parts to force an indicator to move from a “dirty” to a “clean” status. Furthermore, each relies on specific dish positioning or temperature changes to operate properly. The '458 and '872 patents both require that dirty dishes be positioned and weighted on the indicator device so that levers within the devices function properly. The '458 and '239 patents both require a particular temperature change in order to change the status output. These systems are complicated and not foolproof. If the moving parts fail to work together properly, or if the dishes are not loaded into the machine with the appropriate weight distribution on the indicator, or if the temperature change is insufficient, the indicator may give the user the wrong status.
Other types of dishwasher indicators, such as those disclosed in U.S. Pat. No. 5,467,545 and Des. No. 345,829 are placed on the exterior of the dishwasher and require the user to remember to take action to manually change the indicator status. One drawback of such indicators is that they require two actions—a change of the marker from “Dirty” to “Clean” after the cycle has been run, and an additional change from “Clean” to “Dirty” when the dishwasher has been unloaded. Another drawback is that they do not prompt the user with a visual trigger the same way that interior indicators do because exterior indicators are on the outside of the dishwashing machine while the user is focusing their attention on the dishes inside the dishwashing machine. Consequently, exterior indicators are often overlooked and the confusion as to whether the dishes are clean or dirty persists. It would be advantageous to provide a simple, one-step dishwasher status indicator that is located on the interior of the dishwasher, has no moving parts, and doesn't require a particular position or temperature to operate properly.